+#if defined(HAVE_LIBDW)
+ Dwfl *dwfl = NULL;
+
+ /* Setup module tracking for libdwfl unwinding. */
+ struct process *leader = proc->leader;
+ dwfl = leader->dwfl;
+ if (dwfl == NULL) {
+ static const Dwfl_Callbacks proc_callbacks = {
+ .find_elf = dwfl_linux_proc_find_elf,
+ .find_debuginfo = dwfl_standard_find_debuginfo
+ };
+ dwfl = dwfl_begin(&proc_callbacks);
+ if (dwfl == NULL)
+ fprintf(stderr,
+ "Couldn't initialize libdwfl unwinding "
+ "for process %d: %s\n", leader->pid,
+ dwfl_errmsg (-1));
+ }
+
+ if (dwfl != NULL) {
+ dwfl_report_begin_add(dwfl);
+ if (dwfl_report_elf(dwfl, lib->soname,
+ lib->pathname, -1,
+ (GElf_Addr) lib->base,
+ false) == NULL)
+ fprintf(stderr,
+ "dwfl_report_elf %s@%p (%s) %d: %s\n",
+ lib->soname, lib->base, lib->pathname,
+ proc->pid, dwfl_errmsg (-1));
+ dwfl_report_end(dwfl, NULL, NULL);
+
+ if (options.bt_depth > 0) {
+ if (leader->dwfl == NULL) {
+ int r = dwfl_linux_proc_attach(dwfl,
+ leader->pid,
+ true);
+ if (r == 0)
+ leader->dwfl = dwfl;
+ else {
+ const char *msg;
+ dwfl_end(dwfl);
+ if (r < 0)
+ msg = dwfl_errmsg(-1);
+ else
+ msg = strerror(r);
+ fprintf(stderr, "Couldn't initialize "
+ "libdwfl (for unwinding, prototype import) for "
+ "process %d: %s\n",
+ leader->pid, msg);
+ }
+ }
+ }
+ }
+
+ lib->dwfl = dwfl;
+
+#endif /* defined(HAVE_LIBDW) */
+